Over the past twenty years, portable electronic devices have become very popular. Well known portable devices include personal stereo equipment, navigational aids and communications devices, such as pagers and telephones. Such devices are frequently clipped onto a user's belt or to a convenient nearby object to eliminate the need for the user to hold the device while moving about.
Most recently, portable telephones, including home-based portable telephones, cellular telephones and satellite telephones have become common place. The term “portable telephone” is meant to include all such devices. The United States Federal Communications Commission (FCC) defines portable devices as transmitters whose radiating structures are designed to be used within 20 centimeters of the body of the user. Such portable devices are differentiated from “mobile devices”, which are generally those non-fixed transmitters that are used in such a way that the radiating structure is normally more than 20 centimeters away from the user or others.
Conventional clips for portable telephones and other electronic devices include a housing with an attached cradle for receiving a flange-type mount fixed to the device or carrying bag, such as that shown in U.S. Pat. No. 5,597,102 to Saarikko et al. The cradle is generally open at the top, but includes side and bottom walls and a front wall with a vertical center slot for receiving the mount. The conventional clips further include a latch protruding through an opening in the housing into the cradle. The latch is typically biased forward into the cradle by a metal coil spring. A release button can include legs or tines with biasing surfaces to withdraw the latch from the cradle when the release button is pushed downwardly. When the release button is no longer pushed, a second metal spring can bias the release button back to its upward position, while the first spring biases the latch back into the cradle.
A problem with such conventional clips is that the metal springs can wear out or fail. Another problem is that metal springs can affect electromagnetic fields near the device that is being supported by the clip. The second problem can lead to significant expense because the FCC requires that many portable telephones be tested for radio frequency (RF) exposure to a potential human user. It is common to test such devices for specific absorption rate (SAR) of RF radiation, which under FCC guidelines should be limited to 1.6 watts/kg, as averaged over one gram of tissue. In evaluating compliance with the SAR guidelines, portable devices should be tested based on normal operating conditions. Thus, if the device is to be used in conjunction with a clip, the clip too should be involved with the test. This testing adds significant expense to the manufacture of portable devices.
A need exists for a clip for portable devices that includes no metal springs and, consequently, will not affect a device's SAR or require the device and the clip to be tested.